Configurar certificados SSL para la conexión TCP mediante Go

Configura los certificados SSL (capa de conexión segura) para una conexión TCP a Cloud SQL para MySQL mediante el paquete database/sql de Go.

Muestra de código

Go

Para autenticarte en Cloud SQL para MySQL, configura las credenciales predeterminadas de la aplicación. Si deseas obtener más información, consulta Configura la autenticación para un entorno de desarrollo local.

package cloudsql

import (
	"crypto/tls"
	"crypto/x509"
	"database/sql"
	"errors"
	"fmt"
	"log"
	"os"

	"github.com/go-sql-driver/mysql"
)

// connectTCPSocket initializes a TCP connection pool for a Cloud SQL
// instance of MySQL.
func connectTCPSocket() (*sql.DB, error) {
	mustGetenv := func(k string) string {
		v := os.Getenv(k)
		if v == "" {
			log.Fatalf("Fatal Error in connect_tcp.go: %s environment variable not set.", k)
		}
		return v
	}
	// Note: Saving credentials in environment variables is convenient, but not
	// secure - consider a more secure solution such as
	// Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
	// keep secrets safe.
	var (
		dbUser    = mustGetenv("DB_USER")       // e.g. 'my-db-user'
		dbPwd     = mustGetenv("DB_PASS")       // e.g. 'my-db-password'
		dbName    = mustGetenv("DB_NAME")       // e.g. 'my-database'
		dbPort    = mustGetenv("DB_PORT")       // e.g. '3306'
		dbTCPHost = mustGetenv("INSTANCE_HOST") // e.g. '127.0.0.1' ('172.17.0.1' if deployed to GAE Flex)
	)

	dbURI := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?parseTime=true",
		dbUser, dbPwd, dbTCPHost, dbPort, dbName)

	// (OPTIONAL) Configure SSL certificates
	// For deployments that connect directly to a Cloud SQL instance without
	// using the Cloud SQL Proxy, configuring SSL certificates will ensure the
	// connection is encrypted.
	if dbRootCert, ok := os.LookupEnv("DB_ROOT_CERT"); ok { // e.g., '/path/to/my/server-ca.pem'
		var (
			dbCert = mustGetenv("DB_CERT") // e.g. '/path/to/my/client-cert.pem'
			dbKey  = mustGetenv("DB_KEY")  // e.g. '/path/to/my/client-key.pem'
		)
		pool := x509.NewCertPool()
		pem, err := os.ReadFile(dbRootCert)
		if err != nil {
			return nil, err
		}
		if ok := pool.AppendCertsFromPEM(pem); !ok {
			return nil, errors.New("unable to append root cert to pool")
		}
		cert, err := tls.LoadX509KeyPair(dbCert, dbKey)
		if err != nil {
			return nil, err
		}
		mysql.RegisterTLSConfig("cloudsql", &tls.Config{
			RootCAs:      pool,
			Certificates: []tls.Certificate{cert},
			// InsecureSkipVerify and a custom VerifyPeerCertificate function is
			// required to handle Cloud SQL's custom certificates.
			// As an alternative it's also possible to inspect the server
			// certificate and extract the SAN field and use that a ServerName
			// while removing InsecureSkipVerify and VerifyPeerCertificate.
			InsecureSkipVerify:    true,
			VerifyPeerCertificate: verifyPeerCertFunc(pool),
		})
		dbURI += "&tls=cloudsql"
	}

	// dbPool is the pool of database connections.
	dbPool, err := sql.Open("mysql", dbURI)
	if err != nil {
		return nil, fmt.Errorf("sql.Open: %w", err)
	}

	// ...

	return dbPool, nil
}


// verifyPeerCertFunc returns a function that verifies the peer certificate is
// in the cert pool.
func verifyPeerCertFunc(pool *x509.CertPool) func([][]byte, [][]*x509.Certificate) error {
	return func(rawCerts [][]byte, _ [][]*x509.Certificate) error {
		if len(rawCerts) == 0 {
			return errors.New("no certificates available to verify")
		}

		cert, err := x509.ParseCertificate(rawCerts[0])
		if err != nil {
			return err
		}

		opts := x509.VerifyOptions{Roots: pool}
		if _, err = cert.Verify(opts); err != nil {
			return err
		}
		return nil
	}
}

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